#include <iostream>
#include <map>
#include <vector>
#include <algorithm>
using namespace std;
map<long long int, vector<pair<long long int, long long int>>> mm;
vector<pair<long long int, long long int>> g, gg;
long long int c[3000005], d[3000005];
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
long long int n, a, b;
cin >> n >> a >> b;
for (int i = 1; i <= n; i++) {
long long int x, y;
cin >> x >> y;
if (x / b == y / b) {
mm[(x / b) % a].push_back({x % b, y % b});
}
else {
mm[(x / b) % a].push_back({x % b, b - 1});
mm[(y / b) % a].push_back({0, y % b});
x = (x - x % b + b) / b;
y = (y - y % b - 1) / b;
if (y - x + 1 >= a) {
cout << a * b;
return 0;
}
if (x > y) continue;
if (x % a <= y % a) g.push_back({x % a, y % a});
else {
g.push_back({x % a, a - 1});
g.push_back({0, y % a});
}
}
}
for (auto w : g) {
gg.push_back({w.first, 1});
gg.push_back({w.second + 1, -1});
}
sort(gg.begin(), gg.end());
long long int res = 0;
for (int i = 0; i < gg.size(); i++) {
c[i + 1] = c[i] + gg[i].second;
if (c[i + 1] > 0) res = res + (gg[i + 1].first - gg[i].first) * b;
}
for (auto w : mm) {
int h = lower_bound(gg.begin(), gg.end(), make_pair(w.first + 1, -2ll)) - gg.begin() - 1;
if (c[h + 1]) continue;
g.clear();
for (auto ww : w.second) {
g.push_back({ww.first, 1});
g.push_back({ww.second + 1, -1});
}
sort(g.begin(), g.end());
for (int i = 0; i < g.size(); i++) {
d[i + 1] = d[i] + g[i].second;
if (d[i + 1] > 0) res = res + (g[i + 1].first - g[i].first);
//cout << w.first << " " << g[i].second << " " << g[i].first << " " << res << '\n';
}
}
cout << res;
}
